CN117968823A - Distributed optical fiber sound sensing device and sound detection method - Google Patents
Distributed optical fiber sound sensing device and sound detection method Download PDFInfo
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- CN117968823A CN117968823A CN202410382205.4A CN202410382205A CN117968823A CN 117968823 A CN117968823 A CN 117968823A CN 202410382205 A CN202410382205 A CN 202410382205A CN 117968823 A CN117968823 A CN 117968823A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The embodiment of the invention discloses a distributed optical fiber sound sensing device and a sound detection method, wherein the device comprises the following components: the input end of the acousto-optic frequency shift ring is connected with the output end of the narrow linewidth laser seed source; the laser frequency shift ring includes: the device comprises a coupler, a first erbium-doped fiber amplifier, a filter, a first acousto-optic modulator and an isolator; the input end of the second acoustic optical modulator is connected with the output end of the acousto-optic frequency shift ring; the input end of the second erbium-doped fiber amplifier is connected with the output end of the second acoustic optical modulator; the first port of the circulator is connected with the output end of the amplifier, the second port of the circulator is connected with the sensing optical fiber, and the third port of the circulator is connected with the receiving assembly. The number of frequencies of the laser source is increased, thereby reducing or even eliminating interference blanking points.
Description
Technical Field
The invention relates to the field of optical fiber sensors, in particular to a distributed optical fiber sound sensing device and a sound detection method.
Background
The distributed optical fiber sensor detects external physical quantities around the optical fiber such as temperature, stress, vibration and the like by utilizing various scattered signals fed back by an optical fiber loop, and has been widely applied in various fields. The distributed optical fiber vibration sensor uses the coherent intensity change formed by Rayleigh scattering signals generated in the optical fiber, so that the distributed optical fiber vibration sensor has extremely high detection sensitivity. Such sensors are also known as phase-type optical time domain reflectometers.
The conventional phase optical time domain reflectometer adopts a periodically transmitted pulse single frequency laser source as a light source to be detected, and the pulse formation is generally obtained by modulating a single frequency laser (including a semiconductor laser and a fiber laser) working with a continuous wave through an acousto-optic modulator or an electro-optic modulator. The optical signal transmitted into the fiber to be detected is thus essentially a single-frequency laser source with a slightly broader spectrum, which is affected by the pulse width.
When the single-frequency pulse laser source is transmitted along the optical fiber, the generated Rayleigh scattering signals can interfere with the local signals to generate intensity detection demodulation signals, and the intensity detection demodulation signals can also be obtained by detecting interference signals among the Rayleigh scattering signals generated at different positions. Better detection sensitivity and signal-to-noise ratio can generally be obtained if the intensity of the intensity detection signal corresponding to the scattering location is sufficiently large. Otherwise, if the intensity signal of the corresponding position is very small, the signal to noise ratio of the detected position is often too low, and the sensitivity cannot meet the measurement requirement. The intensity variation of the detection signal mainly comes from the influence of the initial phase variation and the polarization state of the Rayleigh scattering signal of the single-frequency pulse laser source in the optical fiber, and at some interference cancellation points, the signal intensity becomes small, so that the detection of the signal is seriously influenced, and the system performance is deteriorated.
Aiming at the problem that the detection performance is affected by more interference cancellation points of the distributed optical fiber sensor in the prior art, no effective solution exists at present.
Disclosure of Invention
In order to solve the problems, the invention provides a distributed optical fiber sound sensing device and a sound detection method, which are used for repeatedly frequency-shifting a single-frequency pulse laser source to obtain a continuous multi-frequency pulse laser source, so that the frequency number of the laser source is increased, interference cancellation points along the optical fiber direction are further reduced or even eliminated, and the problem that the detection accuracy is influenced by more interference cancellation points in the prior art is solved.
To achieve the above object, an embodiment of the present invention provides a distributed optical fiber sound sensing device, including: the laser device comprises a narrow linewidth laser seed source, a laser source and a laser source, wherein the narrow linewidth laser seed source is used for generating a single-frequency pulse laser source; the input end of the acousto-optic frequency shift ring is connected with the output end of the narrow linewidth laser seed source and is used for converting the single-frequency pulse laser source into a continuous multi-frequency pulse laser source; the acousto-optic frequency shift loop comprises: the device comprises a coupler, a first erbium-doped fiber amplifier, a filter, a first acousto-optic modulator and an isolator; the input end of the second acoustic optical modulator is connected with the output end of the acousto-optic frequency shift ring and is used for cutting the multi-frequency pulse laser source to obtain clustered pulses; the input end of the second erbium-doped fiber amplifier is connected with the output end of the second acoustic optical modulator and is used for amplifying the clustering pulse; the first port of the circulator is connected with the output end of the second erbium-doped fiber amplifier, the second port of the circulator is connected with the sensing optical fiber, and the third port of the circulator is connected with the receiving assembly and is used for sending the amplified clustered pulses to the sensing optical fiber, receiving echo signals returned by the sensing optical fiber and sending the echo signals to the receiving assembly; the receiving component is used for receiving the echo signals, converting the echo signals into electric signals, and carrying out data analysis on the electric signals to obtain sound detection results.
Further optionally, a first input end of the coupler is connected with the narrow linewidth laser seed source, a first output end of the coupler is connected with an input end of the second acoustic optical modulator, a second input end of the coupler is connected with an output end of the isolator, and a second output end of the coupler is connected with an input end of the first erbium-doped fiber amplifier; the output end of the first erbium-doped fiber amplifier is connected with the input end of the filter; the output end of the filter is connected with the input end of the first acousto-optic modulator; the output end of the first acousto-optic modulator is connected with the input end of the isolator.
Further optionally, the second acoustic optical modulator cuts the multi-frequency pulsed laser source into single-cluster pulses or double-cluster pulses.
Further optionally, when the single cluster pulse is cut, the receiving component includes an interferometer, a balance detector, an AD collector and a data analyzer which are sequentially arranged; when the pulse is cut into double clusters, the receiving component comprises an avalanche photoelectric detector, an AD collector and a data analyzer which are sequentially arranged.
Further optionally, the frequency of the modulation harmonic of the first acousto-optic modulator is 5-420MHz.
Further optionally, the interferometer is an unbalanced mach-zehnder interferometer.
On the other hand, the invention also provides a sound detection method, which adopts the distributed optical fiber sound sensing device to detect sound, and comprises the following steps: repeatedly shifting the frequency of the single-frequency pulse laser source to obtain a continuous multi-frequency pulse laser source; clustering the multi-frequency pulse laser sources to obtain clustered pulses; amplifying the clustered pulses and transmitting the amplified clustered pulses to a sensing optical fiber; and receiving an echo signal returned from the sensing optical fiber, converting and analyzing the echo signal to obtain sound information.
Further optionally, the step of repeatedly frequency-shifting the single-frequency pulse laser source to obtain a continuous multi-frequency pulse laser source includes: amplifying and filtering the single-frequency pulse laser source to obtain a laser source to be shifted; carrying out harmonic modulation on the laser source to be frequency shifted to obtain a frequency shifted laser source; and repeatedly amplifying, filtering and modulating the frequency-shifted laser source to obtain a continuous multi-frequency pulse laser source.
Further optionally, the clustered pulses are single clustered pulses or double clustered pulses.
Further optionally, the converting and analyzing the echo signal to obtain sound information includes: when the clustering pulse is a single-cluster pulse, the echo signals are subjected to interference and then are subjected to photoelectric conversion to obtain electric signals, and the electric signals are subjected to AD acquisition and then are subjected to signal analysis to obtain the sound information; when the clustering pulse is a double-cluster pulse, the echo signals are subjected to photoelectric conversion to obtain electric signals, and the electric signals are subjected to AD acquisition and then subjected to signal analysis to obtain the sound information.
The technical scheme has the following beneficial effects: by arranging the acousto-optic frequency shifting ring, the single-frequency pulse laser source is shifted into a multi-frequency pulse laser source, the frequency number of the light source is increased, so that the problem of interference intensity blanking points is reduced or avoided, and the detection accuracy is improved; the erbium-doped fiber amplifier, the coupler and the acousto-optic modulator in the acousto-optic frequency shift ring are matched to finish the generation of multiple frequencies, and the mode of increasing the number of optical frequencies is various; different receiving components are arranged through different clustering conditions of the second acoustic optical modulator so as to meet signal analysis under different conditions, and universality is strong.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a distributed optical fiber sound sensing device according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a distributed optical fiber sound sensing device according to another embodiment of the present invention;
FIG. 3 is a flow chart of a sound detection method provided by an embodiment of the present invention;
fig. 4 is a flowchart of a frequency shift method of a laser source according to an embodiment of the present invention;
fig. 5 is a flowchart of an echo signal processing method according to an embodiment of the present invention.
Reference numerals: 1-a narrow linewidth laser seed source; 2-an acousto-optic frequency shift loop; 201-a coupler; 202-a first erbium-doped fiber amplifier; 203-a filter; 204-a first acousto-optic modulator; 205-an isolator; 3-a second acoustic light modulator; 4-a second erbium-doped fiber amplifier; a 5-circulator; 6-sensing optical fibers; 7-a receiving assembly; 701-avalanche photodetector; a 702-AD collector; 703-a data analyzer; 704-an interferometer; 705-balanced detector.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the prior art, a small part of continuous light output by a narrow linewidth laser seed source is firstly split by a first coupler to serve as local light, and the other part of the continuous light is amplified by an erbium-doped fiber amplifier (EDFA) after being subjected to pulse modulation by an acousto-optic modulator and then is injected into a sensing optical fiber by a circulator; the echo signal scattered by the sensing optical fiber is coherent with local light through the circulator and the second coupler and is received by the balance detector; the output electric signals of the balance detector are acquired through AD and used for vibration signal analysis.
The single-frequency pulse laser source is adopted in the phase type optical time domain reflectometer, so that intensity interference blanking points along the length direction of the optical fiber inevitably exist. A typical technical solution is to increase the frequency of the laser source. For example, two single frequency lasers can be used simultaneously, which reduces the problem of blanking of interference intensity to some extent, but this approach further increases the laser source resulting in a system that is overly complex and significantly costly.
In order to solve the above problems in the prior art, an embodiment of the present invention provides a distributed optical fiber sound sensing device, and fig. 1 is a schematic structural diagram of the distributed optical fiber sound sensing device provided in the embodiment of the present invention, as shown in fig. 1, the device includes: the narrow linewidth laser seed source 1, the narrow linewidth laser seed source 1 is used for generating a single-frequency pulse laser source; the input end of the acousto-optic frequency shift ring 2 is connected with the output end of the narrow linewidth laser seed source 1 and is used for converting a single-frequency pulse laser source into a continuous multi-frequency pulse laser source; the acousto-optic frequency shift loop 2 comprises: a coupler 201, a first erbium-doped fiber amplifier 202, a filter 203, a first acousto-optic modulator 204, and an isolator 205; the input end of the second acoustic optical modulator 3 is connected with the output end of the acousto-optic frequency shift ring 2 and is used for cutting the multi-frequency pulse laser source to obtain clustered pulses; the second erbium-doped optical fiber amplifier 4, the input end of the second erbium-doped optical fiber amplifier 4 is connected with the output end of the second acoustic optical modulator 3, and is used for amplifying the clustered pulses; the circulator 5, a first port of the circulator 5 is connected with the output end of the second erbium-doped optical fiber amplifier 4, a second port is connected with the sensing optical fiber 6, and a third port is connected with the receiving component 7 and is used for sending amplified clustered pulses to the sensing optical fiber 6, receiving echo signals returned by the sensing optical fiber 6 and sending the echo signals to the receiving component 7; the receiving component 7 is configured to receive the echo signal and convert the echo signal into an electrical signal, and perform data analysis on the electrical signal to obtain a sound detection result.
As shown in fig. 1, the distributed optical fiber sound sensing device comprises a conventional single-frequency narrow-linewidth laser, wherein the single-frequency narrow-linewidth laser is connected with an acousto-optic frequency shift ring 2, and the acousto-optic frequency shift ring 2 can repeatedly shift the frequency of the seed light output by the single-frequency narrow-linewidth laser, so that a continuous multi-frequency pulse laser source is obtained.
The acousto-optic frequency shift loop 2 comprises: a coupler 201, a first erbium doped fiber amplifier 202, a filter 203, a first acousto-optic modulator 204, and an isolator 205. Wherein, the number of frequencies can be increased by repeatedly shifting the frequency through the first acousto-optic modulator 204; the number of frequencies of light generated by the acousto-optic frequency shift loop 2 can be adjusted by changing the gain of the first erbium-doped fiber amplifier 202; the number of optical frequencies output by the acousto-optic frequency shift loop 2 can be changed to a certain extent by adjusting the coupling ratio of the optical fiber coupler 201.
As an alternative embodiment, the order of connection of the devices in the acousto-optic frequency shift loop 2 may be varied.
The narrow linewidth laser seed source 1 and the acousto-optic frequency shift ring 2 are connected and combined, so that the light source is changed from a single-frequency pulse laser source to a multi-frequency pulse laser source.
In addition, the distributed optical fiber sound sensing device further comprises a second sound modulator 3, a second erbium-doped optical fiber amplifier 4 and a circulator 5, the multi-frequency pulse laser source enters the second sound modulator 3, the multi-frequency pulse laser source is clustered through pulse modulation, the obtained clustered pulses are input into the sensing optical fiber 6 after being subjected to gain through the second erbium-doped optical fiber amplifier 4, the circulator 5 receives echo signals returned by the sensing optical fiber 6, and the echo signals are transmitted to a receiving assembly 7 to be subjected to interference, photoelectric conversion, AD acquisition and other operations and then subjected to data analysis, so that sound information is obtained.
As an alternative embodiment, the first input end of the coupler 201 is connected to the narrow linewidth laser seed source 1, the first output end is connected to the input end of the second acoustic modulator 3, the second input end is connected to the output end of the isolator 205, and the second output end is connected to the input end of the first erbium-doped fiber amplifier 202; the output end of the first erbium-doped fiber amplifier 202 is connected with the input end of the filter 203; the output end of the filter 203 is connected with the input end of the first acousto-optic modulator 204; an output of the first acousto-optic modulator 204 is connected to an input of an isolator 205.
As shown in fig. 1, two input ends of the coupler 201 are respectively connected to an output end of the narrow linewidth laser seed source 1 and an output end of the isolator 205, and the two output ends are respectively connected to an input end of the first erbium-doped fiber amplifier 202 and an input end of the second acoustic optical modulator 3. The coupler 201 may be configured to input the single-frequency pulse laser source emitted from the narrow-linewidth laser seed source 1 to the first erbium-doped fiber amplifier 202 in the guide ring of the single-frequency pulse laser source, or may be configured to input the multi-frequency pulse laser source shifted by the acousto-optic shift ring 2 to the second acoustic optical modulator 3.
The single-frequency pulse laser source output by the narrow linewidth laser seed source 1 enters a filter 203 for filtering, then enters a first acousto-optic modulator 204 for frequency shifting through harmonic modulation, then is conducted in a unidirectional mode through an isolator 205 to remove reflection interference and echo noise, then is input into a coupler 201 again, is coupled through the coupler 201, and can be input into an acousto-optic frequency shifting ring 2 again for repeated frequency shifting to obtain a continuous multi-frequency pulse laser source for input into a second acousto-optic modulator 3.
As an alternative embodiment, the second acoustic optical modulator 3 cuts the multi-frequency pulsed laser source into single-cluster pulses or double-cluster pulses.
The second acoustic optical modulator 3 may cut the multi-frequency pulse laser source by a preset condition, thereby obtaining a single cluster pulse (single pulse output) or a double cluster pulse (double pulse output). The preset conditions can be set manually according to actual conditions.
As an alternative embodiment, the receiving component 7 comprises, when cutting into single cluster pulses, an interferometer 704, a balance detector 705, an AD collector 702 and a data analyzer 703 arranged in that order; when cutting into double cluster pulses, the receiving assembly 7 includes an avalanche photodetector 701, an AD collector 702, and a data analyzer 703, which are arranged in this order.
Fig. 2 is a schematic structural diagram of a distributed optical fiber sound sensing device according to another embodiment of the present invention, as shown in fig. 2, when the second acoustic modulator 3 cuts the multi-frequency pulse laser source into single-cluster pulses, the receiving assembly 7 includes an interferometer 704, a balance detector 705, an AD collector 702 and a data analyzer 703, which are sequentially arranged.
The circulator 5 receives the echo signals scattered by the sensing optical fiber 6, inputs the echo signals into the interferometer 704 for interference, converts the echo signals into electric signals through the balance detector 705, and analyzes the electric signals after AD acquisition, digital-to-analog conversion and demodulation to obtain external vibration signals to be detected.
As shown in fig. 1, when the second acoustic optical modulator 3 cuts the multi-frequency pulse laser source into double-cluster pulses, the receiving assembly 7 includes an avalanche photodetector 701, an AD collector 702, and a data analyzer 703, which are disposed in this order.
The circulator 5 receives the echo signal scattered by the sensing optical fiber 6, inputs the echo signal into the avalanche photodetector 701 to output an electric signal, and analyzes the electric signal after AD acquisition, digital-to-analog conversion and demodulation to obtain an external vibration signal to be detected.
As an alternative embodiment, the frequency of the modulated harmonic of the first acousto-optic modulator 204 is 5-420MHz.
Preferably, the frequency of the harmonic is 100MHz, so that each pass of light can shift its frequency by 100MHz, and the shift is repeated to obtain light of multiple frequencies.
As an alternative embodiment, the interferometer 704 is an unbalanced mach-zehnder interferometer.
The unbalanced Mach-Zehnder interferometer is an instrument for generating double beams by an amplitude division method to realize interference, and can generate double-path echoes based on a single-path echo to realize interference.
The embodiment of the invention also provides a sound detection method, which adopts the distributed optical fiber sound sensing device to detect sound, and fig. 3 is a flow chart of the sound detection method provided by the embodiment of the invention, as shown in fig. 3, and the method comprises the following steps:
S1, repeatedly shifting the frequency of a single-frequency pulse laser source to obtain a continuous multi-frequency pulse laser source;
s2, clustering the multi-frequency pulse laser source to obtain clustered pulses;
S3, amplifying the clustered pulses and then transmitting the amplified clustered pulses to a sensing optical fiber;
And S4, receiving the echo signals returned from the sensing optical fiber, converting the echo signals and analyzing the echo signals to obtain sound information.
A single-frequency narrow linewidth laser generates single-frequency pulse laser, and the single-frequency pulse laser enters an acousto-optic frequency shift ring to carry out repeated frequency shift so as to obtain a continuous multi-frequency pulse laser source. The multi-frequency pulse laser source enters the second acoustic optical modulator to be clustered, so as to obtain clustered pulses, and the clustered pulses are amplified by the second erbium-doped amplifier and then transmitted to the sensing optical fiber through the circulator. The clustering conditions are selected according to actual requirements.
The circulator receives the echo signals returned by the sensing light, and transmits the echo signals to the receiving assembly to convert and analyze the echo signals so as to obtain sound information.
As an alternative implementation manner, fig. 4 is a flowchart of a method for frequency shifting a laser source according to an embodiment of the present invention, where, as shown in fig. 4, frequency shifting is performed on a single-frequency pulse laser source repeatedly, so as to obtain a continuous multi-frequency pulse laser source, where the method includes:
S101, amplifying and filtering a single-frequency pulse laser source to obtain a laser source to be shifted;
s102, carrying out harmonic modulation on a laser source to be shifted to obtain a frequency-shifted laser source;
S103, amplifying, filtering and modulating the frequency-shifted laser source repeatedly to obtain the continuous multi-frequency pulse laser source.
The single-frequency pulse laser source is guided to a first erbium-doped optical fiber amplifier in an acousto-optic frequency shift ring through a coupler to gain, then the single-frequency pulse laser source enters a filter to filter, then enters a first acousto-optic modulator to shift frequency through harmonic modulation, then is conducted in a unidirectional mode through an isolator to remove reflection interference and echo noise, then is input into the coupler again, is coupled through the coupler, and can be input into the acousto-optic frequency shift ring again to repeat frequency shift, so that a continuous multi-frequency pulse laser source is input into a second acousto-optic modulator.
As an alternative embodiment, the clustered pulses are single cluster pulses or double cluster pulses.
As an optional implementation manner, fig. 5 is a flowchart of an echo signal processing method provided by an embodiment of the present invention, where, as shown in fig. 5, an echo signal is converted and parsed to obtain sound information, where the method includes:
s401, when the clustering pulse is a single-cluster pulse, performing photoelectric conversion on the echo signals after interference to obtain electric signals, and performing AD acquisition and signal analysis on the electric signals to obtain sound information;
The circulator receives echo signals scattered by the sensing optical fibers, inputs the echo signals into the interferometer to interfere, converts the echo signals into electric signals through the balance detector, and performs demodulation analysis after AD acquisition through the AD acquisition device to obtain external vibration signals to be detected.
And S402, when the clustering pulse is a double-cluster pulse, performing photoelectric conversion on the echo signal to obtain an electric signal, and performing AD acquisition and signal analysis on the electric signal to obtain sound information.
The circulator receives echo signals scattered by the sensing optical fiber, inputs the echo signals into the avalanche photoelectric detector to output electric signals, and performs demodulation analysis on the electric signals after AD acquisition to obtain external vibration signals to be detected.
The technical scheme has the following beneficial effects: by arranging the acousto-optic frequency shifting ring, the single-frequency pulse laser source is shifted into a multi-frequency pulse laser source, the frequency number of the light source is increased, so that the problem of interference intensity blanking points is reduced or avoided, and the detection accuracy is improved; the erbium-doped fiber amplifier, the coupler and the acousto-optic modulator in the acousto-optic frequency shift ring are matched to finish the generation of multiple frequencies, and the mode of increasing the number of optical frequencies is various; different receiving components are arranged through different clustering conditions of the second acoustic optical modulator so as to meet signal analysis under different conditions, and universality is strong.
The foregoing description of the embodiments of the present invention further provides a detailed description of the objects, technical solutions and advantages of the present invention, and it should be understood that the foregoing description is only illustrative of the embodiments of the present invention and is not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements, etc. that fall within the spirit and principles of the present invention should be included in the scope of the present invention.
Claims (10)
1. A distributed optical fiber sound sensing device, comprising:
The laser device comprises a narrow linewidth laser seed source, a laser source and a laser source, wherein the narrow linewidth laser seed source is used for generating a single-frequency pulse laser source;
The input end of the acousto-optic frequency shift ring is connected with the output end of the narrow linewidth laser seed source and is used for converting the single-frequency pulse laser source into a continuous multi-frequency pulse laser source; the acousto-optic frequency shift loop comprises: the device comprises a coupler, a first erbium-doped fiber amplifier, a filter, a first acousto-optic modulator and an isolator;
the input end of the second acoustic optical modulator is connected with the output end of the acousto-optic frequency shift ring and is used for cutting the multi-frequency pulse laser source to obtain clustered pulses;
the input end of the second erbium-doped fiber amplifier is connected with the output end of the second acoustic optical modulator and is used for amplifying the clustering pulse;
The first port of the circulator is connected with the output end of the second erbium-doped fiber amplifier, the second port of the circulator is connected with the sensing optical fiber, and the third port of the circulator is connected with the receiving assembly and is used for sending the amplified clustered pulses to the sensing optical fiber, receiving echo signals returned by the sensing optical fiber and sending the echo signals to the receiving assembly;
the receiving component is used for receiving the echo signals, converting the echo signals into electric signals, and carrying out data analysis on the electric signals to obtain sound detection results.
2. A distributed optical fiber sound sensing device according to claim 1, wherein:
the first input end of the coupler is connected with the narrow linewidth laser seed source, the first output end of the coupler is connected with the input end of the second acoustic optical modulator, the second input end of the coupler is connected with the output end of the isolator, and the second output end of the coupler is connected with the input end of the first erbium-doped fiber amplifier;
The output end of the first erbium-doped fiber amplifier is connected with the input end of the filter;
The output end of the filter is connected with the input end of the first acousto-optic modulator;
the output end of the first acousto-optic modulator is connected with the input end of the isolator.
3. A distributed optical fiber sound sensing device according to claim 1, wherein:
The second acoustic optical modulator cuts the multi-frequency pulse laser source into single-cluster pulses or double-cluster pulses.
4. A distributed optical fiber sound sensing device according to claim 3, wherein:
when the pulse is cut into single cluster pulses, the receiving component comprises an interferometer, a balance detector, an AD collector and a data analyzer which are sequentially arranged;
when the pulse is cut into double clusters, the receiving component comprises an avalanche photoelectric detector, an AD collector and a data analyzer which are sequentially arranged.
5. A distributed optical fiber sound sensing device according to claim 1, wherein:
The frequency of the modulation harmonic wave of the first acousto-optic modulator is 5-420MHz.
6. The distributed optical fiber sound sensing device of claim 4 wherein:
The interferometer is an unbalanced Mach-Zehnder interferometer.
7. A sound detection method, characterized in that the distributed optical fiber sound sensing device according to any one of claims 1 to 6 is used for sound detection, comprising:
Repeatedly shifting the frequency of the single-frequency pulse laser source to obtain a continuous multi-frequency pulse laser source;
clustering the multi-frequency pulse laser sources to obtain clustered pulses;
amplifying the clustered pulses and transmitting the amplified clustered pulses to a sensing optical fiber;
and receiving an echo signal returned from the sensing optical fiber, converting and analyzing the echo signal to obtain sound information.
8. The method of claim 7, wherein the repeatedly frequency shifting the single frequency pulse laser source to obtain a continuous multi-frequency pulse laser source comprises:
amplifying and filtering the single-frequency pulse laser source to obtain a laser source to be shifted;
carrying out harmonic modulation on the laser source to be frequency shifted to obtain a frequency shifted laser source;
and repeatedly amplifying, filtering and modulating the frequency-shifted laser source to obtain a continuous multi-frequency pulse laser source.
9. The sound detection method according to claim 7, wherein:
The clustering pulse is a single-cluster pulse or a double-cluster pulse.
10. The method of claim 9, wherein converting and analyzing the echo signal to obtain sound information comprises:
when the clustering pulse is a single-cluster pulse, the echo signals are subjected to interference and then are subjected to photoelectric conversion to obtain electric signals, and the electric signals are subjected to AD acquisition and then are subjected to signal analysis to obtain the sound information;
When the clustering pulse is a double-cluster pulse, the echo signals are subjected to photoelectric conversion to obtain electric signals, and the electric signals are subjected to AD acquisition and then subjected to signal analysis to obtain the sound information.
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